Investigation of annealing effects on indium tin oxide thin films by electron energy loss spectroscopy

Indium tin oxide (ITO) thin films have been deposited on substrates by the thermal evaporation method, followed by annealing in air. Post annealing ef fects on the composition and quality of ITO thin films were characterized b y electron energy loss spectroscopy (EELS), X-ray photoelectron spectroscop y (XPS) and Auger electron spectroscopy (AES). Spectroscopic and optical me asurements showed that the low transparency of an as-deposited ITO film was mainly caused by diffusing species which probably consisted of reduced met allic indium particles and defects in the film formed during the preparatio n. EELS results revealed that these metallic indium particles could be remo ved by an annealing process leading to uniformly transparent conducting fil m. This work demonstrates that EELS is a sensitive method to diagnose the p resence of the metallic indium in ITO films. (C) 2000 Elsevier Science S.A. All rights reserved.